ABSTRACT:
Our work has concentrated
in general on time-cognizant trigger processing systems and distributed
mobile computing systems. We designed a performance model for studying
the performance of various components of a distributed trigger processing
system, and conducted experiments to be able to address the performance issues
in executing time-constrained transactions that are triggered under various
types of workload models. We employed a variety of transaction-processing
architectures in the experiments. We also considered different types of
semantics in controlling the concurrent execution of triggered transactions.
Our work on distributed mobile computing systems involved modeling the
position of moving objects, managing the location of moving objects,
indexing dynamic attributes of moving objects, and optimization of
communication cost through caching in mobile environments.
We adapted a variant of the quadtree structure to solve the problem
of indexing dynamic attributes of moving objects. We proposed an algorithm
for regenerating the quadtree-based index periodically that is optimal in
CPU and disk access cost. We also provided an experimental study of performance
focusing on query processing and index update overheads.